ZOLL X-Series Monitor
UX Redesign Concept

An image of a Zoll monitor user interface


Monitors, such as the Zoll X-Series, are often used in emergency situations and pre-hospital care. The Zoll monitor features an electronic display and is used by multiple types of personnel in high-stress situations, making UX a crucial component of this machine.

Key Features

  • Monitoring vital signs such as blood pressure, pulse oximetry, respiration rate, and more

  • 4-lead and 12-lead capabilities

  • Real-time transmissions and charting through Wi-Fi

  • Pediatric attachments for monitoring pediatric patient vitals

  • Defibrillation

  • EtCO2 monitoring (end-tidal volume)

  • Synchronized cardioversion

  • And much more


    While the Zoll monitor has a multitude of functions, it is not always user-friendly. For new healthcare workers or those who do not use the machine often, the user experience can be frustrating and slow down patient care. I chose two main issues to focus on for this concept:
    • A cluttered and outdated interface makes the product needlessly difficult to get acquainted with.
    • The 12-lead setup process is one of the most commonly used functions, yet it is tricky and unforgiving, which can lead to errors in patient data.


    I recreated a Zoll monitor interface using Figma, where I then designed a concept for both of these screens that I believe would help resolve these issues going forward:
    • By rethinking the user interface on the main screen, we can create a more intuitive process which could help new providers learn faster and make fewer mistakes.
    • Adjusting buttons and providing additional visual feedback during the 12-lead setup process makes it much easier to catch mistakes before it's too late, which can lead to more accurate patient data and a faster setup time.


    I wanted a simple, practical solution to both of these issues. My constraints included:
    • Using existing technology to make sure designs are realistic
    • Ensuring no other functionality is lost (for example, revisions to buttons still include different shapes or staggering to help users identify buttons by touch)
    • Staying within the original design dimensions, including the screen and surrounding interface

    User Persona: Carlos

    Task: 12-Lead Setup Process

    A still image from a video showing a Zoll monitor in use
    Figure A: Still from Sears, 12-Lead ECG Process on the ZOLL X Series-ZOLL Tips and Tricks (2:31)
    On a recent call, Carlos was asked to set up a 12-lead on the patient. Carlos applied the leads in the appropriate places and went to the monitor to enter the patient’s demographics and initiate the ECG. 

    Entering Patient Information

    To enter the patient’s age and sex, Carlos must choose from a list of options on the screen.

    The monitor does not have dedicated buttons for all features but uses softkeys, which means the buttons are changed programmatically and may be used for different situations depending on the screen or device feature being used.

    This can be confusing in a situation where the device user must navigate left to right to move from choosing sex to age.

    Arrow Keys with Multiple Functions

    In this situation, Carlos must use the arrow keys to go left and right as well as up and down, while clicking the “enter” button (a button with a circle in the middle as its only description) in between.

    In Figure B (below), you can see the yellow arrow pointing to the “enter” button, and the red circle outlining the left/right and up/down arrows:

    Errors Resulting From Working Quickly

    In this case, Carlos accidentally pressed the buttons in the wrong order and entered the patient as a male, the default setting, when in fact the patient was female.

    Without thinking, Carlos went to press what is normally the “back” button on the monitor. However, with the ECG open, this actually exited the 12-lead completely and he had to start over, causing an unwanted delay.
    A still image from a video showing a Zoll monitor in use
    Figure B: Still from Sears, 12-Lead ECG Process on the ZOLL X Series-ZOLL Tips and Tricks (5:10)
    A still image from a video showing a Zoll monitor in use
    Figure C: Still from Sears, 12-Lead ECG Process on the ZOLL X Series-ZOLL Tips and Tricks (2:31)

    What went wrong here?

    For someone who uses the monitor every day, this is a skill they can acquire over time, and they become used to the limited button options.

    However, for someone who does not use this very often or is in a high-stress emergency situation, this can be quite frustrating. Additionally, the soft keys are offset from the icons on the screen.

    Because of the UX law of proximity, this makes it confusing for the user at first glance because it is not initially obvious which key lines up with which icon on the screen.

    Furthermore, some icons have text and some do not, making the layout inconsistent and learnability more difficult. 

    Given this context, it is easy to understand how someone like Carlos could make mistakes when working in a hurry or with a lot of distractions.

    Proposed Improvements

    Main UI Screen

    My next step was to recreate a Zoll monitor in Figma, implementing my proposed revisions to the interface:
    A mockup of a Zoll monitor screen design
    Figure A: Still from Sears, 12-Lead ECG Process on the ZOLL X Series-ZOLL Tips and Tricks (2:31)
    Next, I added notes describing where each change occurred, and what the reasoning behind it was:

    Summary of Main UI Screen Changes

    Status bar was reorganized to make it easier to see the current date and time
    The “some alarms disabled” alert was changed to a bright color on a black background for higher contrast. The alert was also placed in a visible but more organized spot to maximize screen usage.
    The audio on/off buttons were divided in 2 with recognizable icons and a description
    The “home” and “display” buttons were split into 2 buttons as well, with a recognizable icon on each button and a description for each one.
    Rather than a circle icon with no description, the select button now has a “select” description on it as well. Additionally, instead of 2 arrows with multiple functions, there is a simple 4-button navigation for up, down, left, and right. This will be more intuitive for users who have used other similar navigation functions, such as on a remote control, according to Jakob’s Law. 
    The “snapshot” button now has a label as well as a description letting the user know it will record a 24 second snapshot, reducing ambiguity.
    The button that allows the user to start/stop taking blood pressure now includes the start/stop description, the “NIBP” above (indicating non-invasive blood pressure), and the icon was changed to a more recognizable icon making it easier for the user to find it.
    The vital signs are boxed together in a color-coded box, making it easier to read and recognize according to the principle of common region (the boundary box) as well as the law of similarity (the color coding used here.)
    The defibrillator functions were grouped together inside a boundary box as well, according to the principle of common region. Additionally, the box is labeled with the word “defibrillate”. This makes it easier for someone who does not often use the device to find and use it quickly during a high-stress emergency situation.
    The soft keys now include a line that points directly toward the on-screen label, unlike the previous version which was offset to the point where it was not immediately obvious to the user which key corresponded with which label on the screen, due to the law of uniform connectedness.
    The previous version of this device had ambiguous icons on some of the screen labels, and other ones simply contained text, such as “CO2”. I decided to take the most simple, straightforward route and remove as much guesswork as possible by eliminating icons (such as the print icon, which resembled toilet paper at first glance, and was not the standard print icon we see on most devices.) Each button is labeled with text as clearly as possible within the space given. This allows the user to make the choice with the fewest assumptions.
    Last, I included numbers on each softkey so they can be verbally referenced quickly without having to stop and figure out which button someone is referring to, also helping to remove assumptions and allowing the users to work more efficiently under stress. 

    12-Lead Process Revisions

    I then recreated a mockup of the 12-lead setup on a Zoll monitor. My goal was to identify three ways to improve this screen that would help people like Carlos be able to work more efficiently and to make the interface more intuitive:
    A mockup of a Zoll monitor design with comments
    I included three comments in the screen below, indicating where each change was made and how it could help benefit the user:
    A mockup of a Zoll monitor design with comments

    Summary of Main UI Screen Changes

    An arrow was added to indicate that the item was selected (visualized here under “Patient Age”) and the user can see an arrow pointing right to indicate the right arrow must be used to navigate to the patient age box, for example. (The right arrow is a new addition described in the last mockup.)
    A check mark was added to indicate the field had been saved (the patient’s age, in this case) and that the user could continue to the next field in the dialog box. This will help eliminate mistakes where the user may run a 12-lead by accident with the wrong information selected because it had not confirmed it was saved before proceeding.
    As described previously, the provider can more easily navigate this screen using the improved arrows and "select" function according to Jakob's Law.

    Next Steps & Further Improvements

    Identify All Use Cases

    Interviewing a variety of users would help identify further areas of improvement. Users could include hospital workers, paramedics, EMTs, and more. Each role has unique use cases that could provide additional insight into how the monitor functions are used.

    Prototype Testing

    By having users in different roles test a prototype, we could gather data on whether these improvements are beneficial in some, all, or none of its use cases.

    Data and KPIs

    Data analysis based on user research and testing could help determine the success of these improvements. Certain metrics for tracking data could include accuracy of patient data, onboarding time for new providers using this monitor, and improved efficiency when taking patient vital signs.


    Lopez, Omar. “Hispanic Man Holding Child on Shoulders.” Unsplash, 31 Dec. 2020, https://unsplash.com/photos/Za03n9MIt4s. Accessed 1 Mar. 2022.

    R Series ALS Operator’s Guide - Zoll. https://www.zoll.com/-/media/public-site/products/r-series-defibrillators/9650-0912-01-sf_w.ashx.

    Sears, Kyle. 12-Lead ECG Process on the ZOLL X Series-ZOLL Tips and Tricks, Youtube, 11 June 2020, https://www.youtube.com/watch?v=A4P4_xujDk4 . Accessed 1 Mar. 2022.

    Sevilla, Dr. Mike. “Zoll X Series Monitor Defibrillator.” Medical Equipment Supplier from Major Brands At Affordable Prices, Dr. Mike Sevilla, https://cardomedical.com/product/zoll-x-series/.

    “X Series® Operator’s Guide.” Zoll Medical Corporation, Jan. 2018.

    “Zoll Medical Corporation.” Medical Devices and Technology Solutions - ZOLL Medical, https://www.zoll.com/